1. Field of the Invention
The present invention relates to a high-performance and high-efficiency fin tube for a heat-exchanger and a forming disk for fabricating the same.
2. Background of the Related Art
A fin tube is a tube where prominent and depressed portions are formed alternately on the outer peripheral surface of the tube along the longitudinal direction thereof, in order to facilitate the heat transfer of the tube, through which a fluid passes. In this fin tube, due to the extended area of the outer surface, an efficient heat transfer can be carried out between a heat medium positioned outside the tube and a heat transfer medium flowing inside the tube.
Therefore, these fin tubes are mainly utilized in a heat exchanger, and ceaseless efforts have been made in order to achieve a high-performance and high-efficiency heat exchanger.
In the case where a liquid flows inside a tube and a gas flows outside the tube, a heat transfer coefficient outside the tube is very small relative to the heat transfer coefficient inside of the tube. The ratio between the heat transfer coefficients is approximately less than one twentieth ( 1/20). This means that the heat transfer resistance outside the tube, where a gas flows, is above 20 times that inside the tube. In order to reduce the outside heat transfer resistance, a fin is attached outside the tube to thereby increase the area for heat transferring.
The present invention relates to a change in the shape of fin in order to increase the heat transfer coefficient, i.e., the surface of the flat rolled fin is made to be curved to thereby increase its heat transfer coefficient. A basic concept therefore is disclosed in Korean Utility Model Registration No. 20-200314025 (registered on May 9, 2003). In the present invention, however, a fin tube having an optimum structure and conditions for increasing heat transfer is disclosed. Also, a forming disk for form-rolling this fin tube is disclosed. That is, the present invention relates to a second-generation technology for further developing and implementing the concept disclosed in the above registered utility model.